PSLE A rectangular block B was cut along the dotted line into two smaller rectangular blocks of equal height, C and D, as shown. The volume of D is 16800 cm
3 more than that of C.
- What is the height of each block?
- Riordan packed 6 of block D such that they fit exactly into a box with a square base. The box has the same height as D. At most, how many of block C can be packed into such a box?
(a)
Base area of Block C
= 12 x 28
= 336 cm
2 Base area of Block D
= 42 x 28
= 1176 cm
2 Base area of Block D more than Block C
= 1176 - 336
= 840 cm
2 Height of each block
= 16800 ÷ 840
= 20 cm
(b)
Base area of the box
= 6 x 1176
= 7056 cm
3 Length of the box
= √7056
= 84 cm
Number of Block C along the length of the box
= 84 ÷ 12
= 7 r 0
Number of Block C along the breadth of the box
= 84 ÷ 28
= 3
Number of Block C to pack into the box at most
= 7 x 3
= 21
Answer(s): (a) 20 cm; (b) 21